[SampleFDO] Treat names in profile as not cold only when profile symbol list
is available
In rL372232, we treated names showing up in profile as not cold when
profile-sample-accurate is enabled. This caused 70k size regression in
Chrome/Android. The patch put a guard and only enable the change when
profile symbol list is available, i.e., keep the old behavior when profile
symbol list is not available.
Differential Revision: https://reviews.llvm.org/D67931
llvm-svn: 372665
diff --git a/llvm/lib/Transforms/IPO/SampleProfile.cpp b/llvm/lib/Transforms/IPO/SampleProfile.cpp
index 9c9d851..b647818 100644
--- a/llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ b/llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -1770,27 +1770,32 @@
if (ProfSampleAccEnabled) {
// PSL -- profile symbol list include all the symbols in sampled binary.
// It is used to prevent new functions to be treated as cold.
- // If ProfileSampleAccurate is true or F has profile-sample-accurate
- // attribute, and if there is no profile symbol list read in, initialize
- // all the function entry counts to 0; if there is profile symbol list, only
- // initialize the entry count to 0 when current function is in the list.
- if (!PSL || PSL->contains(F.getName()))
- initialEntryCount = 0;
+ if (PSL) {
+ // Profile symbol list is available, initialize the entry count to 0
+ // only for functions in the list.
+ if (PSL->contains(F.getName()))
+ initialEntryCount = 0;
- // When ProfileSampleAccurate is true, function without sample will be
- // regarded as cold. To minimize the potential negative performance
- // impact it could have, we want to be a little conservative here
- // saying if a function shows up in the profile, no matter as outline
- // function, inline instance or call targets, treat the function as not
- // being cold. This will handle the cases such as most callsites of a
- // function are inlined in sampled binary but not inlined in current
- // build (because of source code drift, imprecise debug information, or
- // the callsites are all cold individually but not cold accumulatively...),
- // so the outline function showing up as cold in sampled binary will
- // actually not be cold after current build.
- StringRef CanonName = FunctionSamples::getCanonicalFnName(F);
- if (NamesInProfile.count(CanonName))
- initialEntryCount = -1;
+ // When ProfileSampleAccurate is true, function without sample will be
+ // regarded as cold. To minimize the potential negative performance
+ // impact it could have, we want to be a little conservative here
+ // saying if a function shows up in the profile, no matter as outline
+ // function, inline instance or call targets, treat the function as not
+ // being cold. This will handle the cases such as most callsites of a
+ // function are inlined in sampled binary but not inlined in current
+ // build (because of source code drift, imprecise debug information, or
+ // the callsites are all cold individually but not cold
+ // accumulatively...), so the outline function showing up as cold in
+ // sampled binary will actually not be cold after current build.
+ StringRef CanonName = FunctionSamples::getCanonicalFnName(F);
+ if (NamesInProfile.count(CanonName))
+ initialEntryCount = -1;
+ } else {
+ // If there is no profile symbol list available, initialize all the
+ // function entry counts to 0. It means all the functions without
+ // profile will be regarded as cold.
+ initialEntryCount = 0;
+ }
}
F.setEntryCount(ProfileCount(initialEntryCount, Function::PCT_Real));